Road Runner has a double rig called the "Buffet Rig".
Mr Crappie has a double rig called the "Troll-Tech"
And there are several others that make multi-arm rigs, some called "A-rigs" & others are known as "Umbrella Rigs". Some are called Ultra-lite and others are designated as "Crappie" specific. Whether or not they're available still ....
I'm thinking that IF they had proved themselves ..... there'd be more chatter about them. Maybe there is and I just haven't kept up with the concept.
The only one I've actually tried is the Road Runner Buffet Rig .... and its jigs tended to run side by side, rather than one over top of the other, at any rate of speed over a very slow retrieve.
They're made with a 1/8oz & 1/16oz head, with the idea that the 1/8oz head will stay under the 1/16oz head. The rig "could be" made to work that way by replacing the 1/8oz head with a 1/4oz head (I think). I haven't tried that, so I'm not sure, but it would seem a viable tweak. I just removed both heads and use them as single RR's.